1. Field of the Invention
The present invention relates to a zoom lens barrel having marks on a zoom operation ring of a fisheye zoom lens barrel.
2. Description of the Related Art
In recent years, a digital single-lens reflex camera using a photoelectric conversion element (image-pickup element) is actively a commercial reality. In a screen size of an image-pickup element of the digital single-lens reflex camera, a Full Size which is the same size as a silver salt film 24×36 mm and an APS-C size or an APS-H size which is a smaller image-pickup surface than the Full Size become mainstreams.
In addition, there is a fisheye zoom lens including both angles of view forming a circular fisheye and a full-frame fisheye for a Full Size image-pickup element.
This fisheye zoom lens, in the digital single-lens reflex camera including the APS-C size or the APS-H size image-pickup element, can obtain an angle of view of the full-frame fisheye in the focal length range. Here, the following will assume a specification where the circular fisheye for the Full Size image-pickup element is formed at a shortest focal length and the full-frame fisheye for the Full Size image-pickup element is formed at a longest focal length. In this case, a user can easily set a focal length forming the circular fisheye or the full-frame fisheye by controlling a zoom operation ring of this fisheye zoom lens barrel to each end. In addition, when zooming from the circular fisheye to the full-frame fisheye in the fisheye zoom lens barrel, since the terms “wide-angle end” and “telephoto end” are not appropriate in a zoom position, this description uses the terms “shortest focal length side or shortest focal length” and “longest focal length side or longest focal length”.
When this fisheye zoom lens barrel is mounted on a camera including the APS-C size or APS-H size image-pickup element, an angle of view of the full-frame fisheye is formed in midstream of a zoom movable range, but it cannot determine what position the zoom operation ring should be set in to obtain the angle of view of the full-frame fisheye. Furthermore, if the zoom operation ring is set at a focal length position where the full-frame fish eye is formed for the predetermined image-pickup element size, it requires positioning the zoom operation ring again when the zoom operation ring is carelessly rotated.
Japanese Utility Model Laid-Open No. 4-130917 discloses a method that provides an appropriate number of a click mechanism temporarily retaining a variable magnification ring at a position of a specific magnification and a magnification indication.
Moreover, Japanese Patent Laid-Open No. 2007-033504 discloses a method that performs lock retention of the zoom operation ring for a lens barrel body.
However, a conventional art disclosed in Japanese Utility Model Laid-Open No. 4-130917 has efficacy for indicating an object distance and a temporary magnification, but does not indicate to a user a focal length forming the circular fisheye or the full-frame fisheye when mounting the zoom lens barrel on cameras including image-pickup element sizes different from each other.
Moreover, a conventional art disclosed in Japanese Patent Laid-Open No. 2007-033504 can lock only in a state where the lens barrel is shortest, and does not have efficacy when a plurality of lock positions is required.